Functional morphology of the mouthparts and gastric mill in Penaeus plebejus Hess (Decapoda : Penaeidea)

Abstract

P. plebejus is both a macrophage and a detritivore. Mouthpart structure of adult P. plebejus is similar to that of other macrophagous decapods, but the proventriculus is less calcified than in reptant decapods and the triturative surfaces of the gastric mill are small. These features have led previous authors to postulate that maceration of large food by penaeids occurs mainly at the mouthparts. In P. plebejus, the mouthparts function as in macrophagous reptant decapods, the food being torn between the mandibles and third maxillipeds and swallowed with little maceration. The proventriculus exhibits a rhythmic macerating action in which shell fragments and sand ingested with the diet play a part. The proventriculus of P. plebejus is functionally analogous to a gizzard.